Most modern vehicles are equipped with a liquid cooling system (referred to herein as a “powertrain cooling system”) that continually circulates a coolant fluid (e.g., antifreeze) to dissipate excess heat generated by the vehicle's internal combustion engine and to provide other heat-transfer functions (e.g., heating of other engine fluids; rapid warming of the engine upon start-up; warming of a heater core included within the vehicle's heating, ventilation, and air conditioning system; etc.). A conventional powertrain cooling system typically includes, amongst other components, a radiator core having a plurality of cooling fins interspersed with a plurality of metal tubes to form a generally rectangular unit, which is mounted between the vehicle's grill and engine compartment. During engine operation, coolant heated by the engine housing (e.g., the engine block and the cylinder head) is supplied to an inlet of the radiator core by an engine-driven centrifugal pump. The heated coolant flows through the radiator tubes and conductively transfers heat to the cooling fins, which are then convectively cooled by exposure to ram airflow received through one or more openings in the vehicle grill and/or by forced airflow directed over the radiator core by a neighboring fan. The airflow convectively heated by the radiator core is then routed to the vehicle's engine compartment to provide additional cooling thereto. After flowing through the radiator core, the coolant fluid is again circulated through the engine housing to repeat the cooling cycle.
Due to the presence of rubber hoses and other heat-sensitive components within the engine compartment, powertrain cooling systems have traditionally been designed to limit the maximum outlet temperature of the radiator; i.e., the maximum temperature to which the radiator convectively heats airflow to which it is exposed. Radiator cores have also traditionally been designed to enable a single radiator core to satisfy a wide range of heat rejection needs. In particular, single radiator cores have traditionally been designed to dissipate relatively small heat loads produced under everyday use conditions (e.g., moderate ambient temperatures, light loading of the vehicle, inactivity or minor demands placed on the vehicle's air conditioning (A/C) system, etc.), as well as relatively large heats loads generated under extreme use conditions (e.g., high ambient temperatures, heavy loading of the vehicle, vehicle towing, major demands placed on the vehicle's A/C system, etc.).
To ensure that the radiator outlet temperature does not become undesirably high under extreme use conditions, conventional powertrain cooling systems are typically designed to intake a substantial volume of airflow through the vehicle grill during forward movement of the vehicle. By exposing the radiator core to such a large volume of airflow, a substantial amount of heat may be rejected (i.e., transferred from the radiator core to the ambient airflow) without causing a significant rise in air temperature immediately downstream of the radiator core. However, the intake of such a large volume of airflow through the vehicle grill results in the exertion of significant aerodynamic drag on the vehicle and a corresponding reduction in fuel economy. Certain powertrain cooling system have been developed that include one or more airflow valves (e.g., shutter-type valve assemblies) that can be closed when the vehicle is operating under everyday use conditions to impede airflow through the vehicle's grill and thereby reduce aerodynamic drag on the vehicle. However, such powertrain cooling systems are still limited in certain respects and generally fail to provide optimal heat rejection-to-fuel consumption ratios over a wide range of operating conditions.
There thus exists an ongoing need to provide embodiments of a fuel efficient powertrain cooling system and a radiator module that achieves a relatively high heat rejection-to-fuel consumption ratio. Ideally, embodiments of such a fuel efficient radiator module would enable the rapid warming of a vehicle's internal combustion engine without requiring rapid warming loops employed by many conventional powertrain cooling systems. Other desirable features and characteristics of the present invention will become apparent from the subsequent Detailed Description and the appended Claims, taken in conjunction with the accompanying Drawings and this Background.